The invention relates to improved techniques for providing tendon or ligament implants that promote regrowth tendon or ligament tissue without immobilizing an associated joint.
Great progress has been made in the replacement of various organs/tissues by homografts, heterografts, and allografts, using either the approach of implanting a non-resorbable permanent substitute of the injured or missing parts using metallic or plastic materials, or by implantation of biodegradable "scaffold" material which serves as a temporary matrix for cell and blood vessel ingrowth. Substitution or repair of tendons and ligaments has been more difficult than substitution or repair of other organs. For example peritendinous adhesions that prevent sliding of a tendon in its sheath may be formed during healing of tendons by ingrowth of fibroblasts into an implant. Numerous polymers and tendon grafts have been tested, but a review of the literature shows no satisfactory solution of the ligament/tendon replacement problem. It is clear that only a few materials can be used to obtain high mechanical strength and simultaneously achieve fast cell ingrowth into a ligament/tendon implant matrix. Most polymers that have been tested do not allow good "association" or junction with the tissue being repaired. Prior implants that provide adequate mechanical strength suffer from the shortcoming that they fail to function well enough as substrates for fibrogenic cell migration to be viable ligament/tendon substitutes. Such materials have poor, weak "association" with the repair tissue. The anastomosis of prior implanted tendon prosthesis to an injured tendon stump or to muscle or bone has created many problems because such anastomosis cannot resist large mechanical stresses without slipping or cutting of sutures through the implanted tendon prosthesis. Furthermore, artificial ligament and tendon substitutes generally have been unsatisfactory because they have been subject to loss of mechanical strength or fragmentation due to fatigue caused by cyclic loading. Also, artificial ligament and tendon substitutes usually have produced chronic inflammatory reactions.
For long it has been known that cadaver tendons/ligaments would be ideal substitutes for injured tendons/ligaments if their antigenicity could be overcome.
Collagen hemostatic felt has been implanted as a ligament and tendon substitute. This is described in the paper "Pure Collagen as a Ligament and Tendon Substitute: A Histological Analysis in Animals", by E. C. Percey, John Medlen, and the present inventor Milos Chvapil, presented by John Medlen at the 1983 annual meeting of the Orthopedic Society of Sports Medicine at Williamsburg, Va.
However, there still is a need for an improved ligament/tendon implant that provides adequate mechanical strength immediately after the implantation, promotes rapid regrowth of ligament/tendon tissue without inflammatory reaction, and which can fulfill various other requirements for the repair/replacement of tendons and ligaments in humans.